Fuel assembly fabrication module

FIG. 10 shows the layout of the fuel assembly assembling module. Fuel assemblies for the SFR, each of which contains fuel rods, are constructed remotely in a hot cell using a single pair of manipulators. The temperature of the fuel rod containing fuel processed using melt refining and containing high concentrations of fission products is above the melting point of sodium as a result of radioactive heating [40]. Therefore, fuel assembly construction occurs in a vertical position.

65 FIG. 8. Detailed flowsheet for metallic fuel rod fabrication.

This arrangement would also allow a high modularity and flexibility to the remote handling equipment in the process cells with specifically limited functions. Process equipment can be designed in a modular approach to maximize the simplicity of transfer process between process cell and maintenance cell because most complex manipulations of equipment would be performed by removing an equipment module from the process cell to the maintenance cell and replacing the module with a spare equipment while maintenance is done.

66

No Name No Name No Name No Name

1 TRU ingot transfer portal 2 TRU metal

storage 3 TRU metal storage 4 Scale for receiving material

5 Scale for receiving material

(backup) 6 Mould storage 7 Injection casting

apparatus 8 Crucible storage 9 Coating material storage 10 Dross storage 11 Dross removal unit 12 Heel removal unit 13 Heel/scrap storage 14 Mould removal

unit 15 Storage for breached mould and dross dust

collection 16 Sample collection and transfer unit 17 fuel slug temporary storage 18 Fuel slug

inspection device 19 Fuel slug storage 20 Slug tray and supply table 21 Rod end fitting storage 22 Bond Na storage 23 Cladding tray and

supply table 24 Na/slug charging device

25 Fuel rod welding and

inspection 26 Ultrasonic test

device 27 He leakage test unit 28 Surface

decontamination device

29 Contamination inspection

unit and fuel rod loading table 30 Fuel rod tray and loading table 31

Temporary storage space for replacing

equipment parts 32 Transfer device 33 Fuel rod transfer air lock 34 Waste transfer

air lock 35 Fuel material transfer

airlock 36 Shielding windows

FIG. 9. Layout of the SFR fuel rod fabrication module.

Fuel rod fabrication system

67 I.1.3. Additional design approach for proliferation resistance purpose

Safeguards by design (SBD) is defined as an approach whereby international safeguards requirements and objectives are fully integrated into the design process of a nuclear facility, from initial planning through design, construction, operation, and decommissioning [31] and [19]. In this regard, one of the design goals of the process cells is to minimize the number of ways that materials can be transferred and the possibilities for equipment to be manipulated.

These design actions simplify the monitoring of the transfer processes. In addition, to improve the overall facility availability, maintenance cells are located on the second floor, as shown in FIG. 11. These cells are directly over the first floor shown previously in FIG. 6. This construction allows maintenance and refurbishment to be done off-line. The product and waste storage areas are located in the basement below the first floor.

No

. Name No. Name No Name No Name

1 Fuel rod transfer

airlock 2 Transfer device

between cells 3 Fuel rod tray replacing

equipment 4 Empty tray buffer 5 Fuel rod magazine 6 Fuel rod

transport cart 7 Na bonder 8 Fuel rod horizontal transfer and bond tester 9 Wire wrapping device 10

Fuel pin

inspection

device 11 Wire storage 12 Fuel pin loading and assembling machine

13 DUCT assembly table 14 DUCT support 15 Final assembling

machine 16 Fuel assembly inspection device

17 Fuel assembly temporary storage

vault 18 Fuel assembly

exit 19 Maintenance

area 20 Equipment air lock 21 Waste transfer airlock 22 Shielding windows

FIG. 10. Conceptual layout of the SFR fuel assembly assembling module.

68

FIG. 11. Layout of the second floor of the main building.

Overall facility availability may be improved because maintenance and refurbishment can be done off-line. A key issue with separating process and maintenance operations will be the need to reliably remove TRU-bearing material from equipment modules — except for residual contamination — before they are transferred out of a process cell. It is therefore important to have safeguards instrumentation that can assay the residual transuranic material remaining in an equipment module to verify that its complete removal and consistency with declared values.

Likewise, if the number of entry and exit portals into the process cells is minimized, verifications of the consistency of all material additions and removals with declared operation can be reduced.

However, the separation of process and maintenance functions is only required for processes that handle TRU. Processes that handle non-TRU streams (off-gas, separated uranium, cladding hulls, fission products) do not need the same safeguards intensity if transfers into those processes are monitored to confirm that they are consistent with declared operation (e.g., residual transuranic inventories consistent with declared operation). Table 23 shows the list of major equipment in the SFMF facility.

69 TABLE 23. A LIST OF MAJOR EQUIPMENT IN THE SFMF

Equipment of Major Processing

Processing capacity Equip.

Capacity Equipment

Size (meters) Quantity Annual Daily

Raw material temporary storage 45.1

tHM 225.2

kgHM 2250 kgHM 3.0Lx3.0Wx2.0

H 1

Scale for receiving material 45.1

tHM 225.2

kgHM 250

kgHM/day 3

Mould, pellet assembling device 45.1

tHM 225.2

kgHM 250

kgHM/day 1

Injection casting apparatus 45.1 tHM

225.2

kgHM 40 kgHM/day 5.0Lx4.0Wx3.0

H 6

Scale for Crucible 1

Mould removal unit 2.5Lx2.0Wx2.0

H 1

slug inspection device 654 277

ea 3271 ea 3300 ea/day 1.5Lx1.5Wx1.5

H 1

Fuel rod welding and

inspection 327 139

rods 1635 rods 1650

Contamination inspection Unit 327 139

rods 1635 rods 1650

rods/day 1

Ultrasonic test device 327 139

rods 1635 rods 1650

rods/day 1

Na bonding device 327 139

rods 1635 rods 1650

rods/day 1.0ØWx4.0H 3

Bonding inspection device 327 139

rods 635 rods 1650 rods/day

8.0Lx2.0Wx1.5

H 1

Wire wrapping device 327 139

rods 1635 rods 1650

rods/day 5.0Lx6.0Wx1.5

H 1

Fuel rod inspection device 327 139

rods 1635 rods 1650

rods/day 8.5Lx2.0Wx2.0

H 1

Final assembling machine 1207

assemb 6 assemb. 1207 assemb

/day 5.0Lx2.0Wx1.5

H 1

Fuel assembly inspection device 1207

assemb 6 assemb. 1207 assemb

/day 1.0Lx5.0H 1

Rework device 4

I.1.4. Process Materials

The current SFMF is designed for a throughput of 38.62 tHM/year and metal fuel consists of an alloy including about 20% TRU (65U-20TRU-5RE-10Zr: 11.4 ton TRU/year; 327 139 fuel rods/year; 1207 fuel assemblies/year). The TRU feedstock consists of Pu, Am, Np and Cm, as well as recycled U-TRU-RE-Zr process materials (casting heels, fuel slug end crops, out of specification fuel slugs, etc.).

70

In general, the fuel rod fabrication process generates a significant amount of process residues during processing. However, most are recycled back to the process units for reuse, and just small amounts are released to the waste-form fabrication process as final waste. For example, excessive waste is produced during de-moulding, due to shards of broken quartz. The heel is partially covered with oxide dross that is created by the reaction between the alloy and oxygen.

Likewise, it is intended to recover the TRU contained in these wastes, in order to send TRU-free waste to the waste form fabrication process.

I.1.4.1. Process residues

For injection casting, the bottom ends of quartz moulds, the top ends of which are closed, are immersed in the molten alloy. As there is a certain clearance between the bottom of the crucible and the bottom ends of the moulds, following the casting, a small quantity of the melted slugs remains as a hold up. This is known as ‘heel’. The heel occurs from each batch, and is recycled to the melter after removing dross, which is in oxide form. Typically, the heel is about 10% of the initial charged amount. Therefore, in the case of 1 ton/year throughput, about 0.1 ton will occur as heel. However, the amounts generated is fully recycled to the metal fuel preparation unit for reuse, not released as waste.

Fuel slug trimming used for identification of alloy microstructure and chemical characterization will be recycled into the casting process or metal alloy preparation unit. Rejected slugs will also be recycled to process units in order to minimize waste amounts.

Two types of waste forms will be discharged: graphite and quartz composing. Quartz waste can be incorporated into a borosilicate form. However, an appropriate form for graphite has not been identified yet.

I.1.4.2. Oxide wastes

As the residues arising from the metal fuel fabrication, the oxide dross is generated from melts and moulds, respectively. They each come from a result of an oxidation of alloy. For example, Y2O3 coated on graphite crucible can oxidize all elements in alloy as follows:

3Zr (in alloy) + 2 Y2O3 (on graphite)  3ZrO2 + 4Y

On the other hand, it is possible that the outer of mould reacts with melt to generate alloy oxides that can occur as follows:

Zr (in melt) + SiO2 (in quartz)  ZrO2 + Si

Oxide cannot be recycled direct to melter or caster. That can be converted into metal or dissolved in salt for reuse at the pyroprocess units. Dross adhered to outer surface of moulds is dissolved with ZrCl4 and recycled to the electrorefiner to recover actinides, leaving just quartz as waste. Also, dross from heel can go to the electro-reducer to convert oxide into metal, but it is also possible to be dissolved with ZrCl4 to produce a salt including actinides. In that case, the dross from heel can go to the electrorefiner. Accordingly, all oxides generated are dissolved in the salt and then the salt including TRU is recycled to the electro-refiner.

During the metal fuel fabrication, 0.6% of initial charged amounts take place as the dross, but 0.55% is dissolved in LiCl-KCl eutectic salt and the salt is recycled to the electro-refiner. Only 0.05% of the whole dross indicates TRU amounts included in the breached quartz following

71 clean-up of moulds. Eventually, this will be disposed of as final waste after a waste form fabrication. Based on 1 ton/yr throughput of metal fuel, 500 g TRU/year will be incorporated into a waste form.

I.1.4.3. Crucible and breached moulds

The used crucible and breached moulds will be classified as waste. As they include small amounts of TRU, they should go to the cleanup process in order to dissolve TRU in the LiCl-KCl salt before disposing of them. In the case of used crucible, we do not expect many amounts of used crucible to be generated as waste during metal fuel fabrication. The crucible can be continuously used until coated material (Y2O3) is peeled off from graphite crucible.

KAERI estimates a generation rate of used crucible to be 0.5% which means that the used crucible including 5kg alloy (for 1ton/yr throughput) will be generated as waste. Following clean-up process, about 0.5kg alloy will be annually incorporated into a waste form together with crucible material of graphite. This is identical with about 100g TRU.

In the case of breached moulds, as a mould contains about 85g alloy, about 11 800 moulds are required based on a 1 ton/yr throughput. Accordingly, the used quartz amounts are calculated to be about 270kg annually.

– Outer diameter: 6 mm – Inner diameter: 5 mm – Length: 1200 mm – Quartz density: 2.20 g/cm³ – Number of moulds: 11 800

Only 0.5% of initially charged alloy amounts will be generated as waste and 90% of them will be dissolved in the salt during clean-up process, leaving about 500g alloy in breached quartz.

This corresponds to 100g of TRU in 270kg quartz.

I.1.4.4. Process feed and products

Feed ingots, fuel rods and assemblies will need regular inspection to ensure that they comply with metal fuel standards. Acceptance conditions would be:

– Ingots: non-destructive assay. If it should be rejected and recycled, it goes to melter or metal alloy preparation unit.

– Rod: straightness, Na bonding status and welding status are checked and if needed to be recycled, it goes to electrorefiner due to treatment of sodium.

– Assembly: straightness will be confirmed, and if need to be recycled, it goes to fuel rod fabrication process.

Table 24 shows generation ratios of by-products and waste during metal fuel fabrication.

KAERI plans to trim about 10% of initial charged amount. Table 24 also shows that the reject ratios of ingots, rod and fuel assembly are about 3.5%, 5.0% and 0.05%, respectively. However, all materials to be rejected will be recycled to process units for reuse, not releasing them for waste fabrication. At any event, annual generation amounts will be 35 kg for ingots, 50 kg for rod, and 0.5 kg for fuel assembly, respectively, based on a 1 ton/year throughput.

72

TABLE 24. GENERATION RATIOS OF RESIDUES AND WASTE DURING METAL FUEL FABRICATION

Generation

Ratio * Recovery Status Waste Amounts

Heel 0.1 recycled -

Crop 0.098 recycled -

Heel Dross 0.003 recycled -

Used Crucible 0.005 Recycled/waste 0.0005

Mould Dross 0.005 recycled -

Mould - waste 0.0005

Ingots 0.035 recycled -

Pin 0.050 recycled -

Assembly 0.0005 recycled -

Am TBD recycled TBD

Fines TBD recycled TBD

Total 0.251 0.001

* on the basis of initial charged amounts

I.1.4.5. Final waste inventories and form

Although most parts generated as waste are recycled to process units and not released to waste form fabrication process, used crucibles, breached moulds composing of SiO2 are supposed to be disposed of for waste form fabrication without further recovering TRU material of which waste streams also need to meet IAEA safeguards requirement of ‘practically-irrecoverable’ for safeguards to be terminated. The amount of heavy metal contained in the breached moulds is assumed to be 0.5 tons/year and can be incorporated into borosilicate glass form together.

Graphite crucible waste is also assumed to contain 0.5 tons/year, and that a high-temperature, corrosion-resistant ceramics needs to be considered as crucible of melting and casting. The breached moulds and used crucibles will be stored in the universal container for vitrified waste (Universal Container-V: 1338 mm H x 430 mm Ø) which are used at the La Hague reprocessing plant as a standardized container for vitrified waste.

73 REFERENCES

[1] INTERNATIONAL ATOMIC ENERGY AGENCY, Guidance for the Application of an Assessment Methodology for Innovative Nuclear Energy Systems, INPRO Manual – Proliferation Resistance, Volume 5 of the Final Report of Phase 1 of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO), IAEA-TECDOC-1575, IAEA Vienna (2007).

[2] IAEA/INPRO, Terms of Reference of the INPRO Collaborative Project on Proliferation Resistance and Safeguardability Assessment Tools (PROSA), Rev.9 Final 05 June 2012.

[3] THE PROLIFERATION RESISTANCE AND PHYSICAL PROTECTION WORKING GROUP OF THE GENERATION IV INTERNATIONAL FORUM, Evaluation Methodology for Proliferation Resistance and Physical Protection of Generation IV Nuclear Energy Systems, Rev. 6, September 15, (2011).

[4] INTERNATIONAL ATOMIC ENERGY AGENCY, INPRO Collaborative Project:

Proliferation Resistance: Acquisition/Diversion Pathway Analysis (PRADA), IAEA-TECDOC-1684, IAEA Vienna (2012).

[5] INTERNATIONAL ATOMIC ENERGY AGENCY, Statute, As Amended up to 28 December 1989, IAEA (1989).

[6] INTERNATIONAL ATOMIC ENERGY AGENCY, Proliferation Resistance Fundamentals for Future Nuclear Energy Systems, IAEA STR-332, IAEA, Vienna (2002).

[7] INTERNATIONAL ATOMIC ENERGY AGENCY, The Structure and Content of Agreements Between the Agency and States Required in Connection with the Treaty on the Non-Proliferation of Nuclear Weapons, INFCIRC/153(Corrected), IAEA, Vienna (1972).

[8] INTERNATIONAL ATOMIC ENERGY AGENCY, Model Protocol Additional to the Agreement(s) between State(s) and the International Atomic Energy Agency for the Application of Safeguards, INFCIRC/540 (Corrected), IAEA, Vienna (1998).

[9] INTERNATIONAL ATOMIC ENERGY AGENCY, Guidance for the Application of an Assessment Methodology for Innovative Nuclear Energy Systems, INPRO Manual – Overview of the Methodology, Volume 5 of the Final Report of Phase 1 of the International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO), IAEA-TECDOC-1575, IAEA Vienna (2008).

[10] INTERNATIONAL ATOMIC ENERGY AGENCY, Communications Received from Members Regarding the Export of Nuclear Material and of Certain Categories of Equipment and Other Material, INFCIRC/209, IAEA, Vienna (1974).

[11] INTERNATIONAL ATOMIC ENERGY AGENCY, IAEA Safeguards Glossary 2001 Edition, International Nuclear Verification Series No.3, IAEA, Vienna (2002).

[12] INTERNATIONAL ATOMIC ENERGY AGENCY, Communications Received from Certain Member States Regarding Guidelines for the Export of Nuclear Material, Equipment or Technology, INFCIRC/254, IAEA Vienna (1978).

[13] UNITED NATIONS, Security Council Resolution 1540, S/RES/1540 (2004).

[14] INTERNATIONAL ATOMIC ENERGY AGENCY, Guidance for States Implementing Comprehensive Safeguards Agreements and Additional Protocols, IAEA Services Series 21, (2016).

[15] INTERNATIONAL ATOMIC ENERGY AGENCY, Nuclear Material Accounting Handbook, IAEA Services Series No. 15, (2008).

74

[16] INTERNATIONAL ATOMIC ENERGY AGENCY, Multilateral Approaches to the Nuclear Fuel Cycle, Expert Group Report to the Director General of the IAEA, IAEA, Vienna (2005).

[17] INTERNATIONAL ATOMIC ENERGY AGENCY, Safeguards statement for 2019, IAEA, Vienna (2019).

[18] INTERNATIONAL ATOMIC ENERGY AGENCY, International Safeguards in Nuclear Facility Design and Construction, NE Series Document NP-T-2.8, Vienna (2012).

[19] INTERNATIONAL ATOMIC ENERGY AGENCY, Facility Design and Plant Operation Features that Facilitate the Implementation of IAEA Safeguards, IAEA-STR-360, IAEA, Vienna (2009).

[20] INTERNATIONAL ATOMIC ENERGY AGENCY, Design Measures to Facilitate Implementation of Safeguards at Future Water Cooled Nuclear Power Plants, Technical Reports Series No. 392, Vienna, (1998).

[21] INTERNATIONAL ATOMIC ENERGY AGENCY, International Safeguards in the Design of Nuclear Reactors, IAEA Nuclear Energy Series No. NP-T-2.9, IAEA, Vienna, (2014).

[22] INTERNATIONAL ATOMIC ENERGY AGENCY, International Safeguards in the Design of Uranium Conversion Plants, IAEA Nuclear Energy Series No. NF-T-4.8, IAEA, Vienna, (2017).

[23] INTERNATIONAL ATOMIC ENERGY AGENCY, International Safeguards in the Design of Fuel Fabrication Plants, IAEA Nuclear Energy Series No. NF-T-4.7, IAEA, Vienna, (2017).

[24] INTERNATIONAL ATOMIC ENERGY AGENCY, International Safeguards in the Design of Facilities for Long Term Spent Fuel Management, (2018).

[25] INTERNATIONAL ATOMIC ENERGY AGENCY, International Safeguards in the Design of Reprocessing Plants, (2019).

[26] INTERNATIONAL ATOMIC ENERGY AGENCY, International Safeguards in the Design of Enrichment Plants, (2019).

[27] INTERNATIONAL ATOMIC ENERGY AGENCY, Safeguards Techniques and Equipment: 2011 Edition, International Nuclear Verification Series No. 1 (Rev. 2) (2011).

[28] RENDA G., Resisting Nuclear Proliferation Through Design, A System Approach to Nuclear Proliferation Resistance Assessment, A dissertation submitted to the University of Bristol, (2008).

[29] UNITED STATES DEPARTMENT OF ENERGY, Overview of the Facility Safeguardability Analysis (FSA) Process, PNNL-21698, (2012).

[30] UNITED STATES DEPARTMENT OF ENERGY, Trial Application of the Facility Safeguardability Assessment Process to the NuScale SMR Design, PNNL-22000 Rev.1, (2013).

[31] PARK, S.W., Why South Korea Needs Pyroprocessing, Bull. Atom. Scientists, (Oct.26, 2009).

[32] CHANG L. et al., A Case Study for the INPRO Collaborative Project, Proliferation Resistance and Safeguardability Assessment Tools (PROSA), Institute for Nuclear Material Management — 55th Annual Mtg., Atlanta, GA, 20–24 July (2014).

[33] KIM S. K., KO W. I., LEE Y. H., Economic Viability of Metallic Sodium-Cooled Fast Reactor Fuel in Korea, Science and Technology of Nuclear Installations, Volume 2013, Article ID 412349, (2013).

[34] LEE, T-H., et al, Development of a Neutron Coincidence Counter for advanced Spent Fuel Conditioning Process, Journal of the Korean Physical Society, 48, 2, 218 (2006).

75 [35] LEE, T-H., et al, A Direct Non-Destructive Assay for the Pu of U/TRU Ingot in Pyroprocessing Using 244Cm Neutron Albedo Reactivity Technique and Its Error, Nuclear Technology, (2012).

[36] LEE, T-H., et al, Hot-Test Results of the Advanced Spent Fuel Conditioning Process Safeguards Neutron Counter for PWR Spent Fuel, Nuclear Technology, Nucl.

Technol., 176, 147 (2011).

[37] TOBIN, S., et al, Determining Plutonium Mass in Spent Fuel with Non-Destructive Assay Techniques / NGSI Research Overview and Update on NDA Techniques, Part 1, IAEA-CN-184/130, IAEA Safeguards Symposium, Vienna (2010).

[38] LEE, J., South Korea’s Export Control System, Stockholm International Peace Research Institute, (2013).

[39] INTERNATIONAL ATOMIC ENERGY AGENCY, International Target Values 2010 for Measurement Uncertainties in Safeguarding Nuclear Materials, STR-368, Vienna (2010).

[40] BURKES D. E. et al., A US perspective on fast reactor fuel fabrication technology and experience part I: metal fuels and assembly design, Journal of Nuclear Materials, 389, pp. 458–469, (2009).

[41] UNITED STATES OF AMERICA, U.S. Atomic Energy Act, Section 123 (1954).

[42] INTERNATIONAL ATOMIC ENERGY AGENCY, Introduction to the Use of the INPRO methodology in a Nuclear Energy System Assessment, NP-T-1.12, IAEA, Vienna (2010).

[43] INTERNATIONAL ATOMIC ENERGY AGENCY, Terms for Describing New, Advanced Nuclear Power Plants, IAEA, TECDOC-936, Vienna (1997).

[44] BATHKE, C., et al., Implications for Advanced Safeguards Derived from a Proliferation Resistance and Physical Protection Case Study for a Generation IV Nuclear Energy System, Nucl. Technol., 179, 5 (2012).

[45] PELLAUD, B., Proliferation Aspects of Plutonium Recycling, J. Nucl. Mater.

Management, 31, 30 (2002).

[46] KESSLER, G., Plutonium Denaturing by ²³⁸Pu, Nucl. Sci. Eng., 155, 53 (2007).

[47] SAGARA, H., et al., Denaturing of Plutonium by Transmutation of Minor-Actinides for Enhancement of Proliferation Resistance, J. Nucl. Sci. Technol., 42, 161 (2005).

[48] SAITO, M., et al., Development of Methodology for Plutonium Categorization (II) - Improvement of Evaluation Function ‘Attractiveness’, American Nuclear Society

[48] SAITO, M., et al., Development of Methodology for Plutonium Categorization (II) - Improvement of Evaluation Function ‘Attractiveness’, American Nuclear Society

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